Buggy code:
abstract class AnnotatedMixinElementHandler { static class AliasedElementName { protected final String originalName ; private final List < String > aliases ; public AliasedElementName ( Element element , AnnotationMirror annotation ) { } public boolean hasAliases ( ) { } public List < String > getAliases ( ) { } public String elementName ( ) { } public String baseName ( ) { } } static class ShadowElementName extends AnnotatedMixinElementHandler . AliasedElementName { private final boolean hasPrefix ; private final String prefix ; private final String baseName ; private String obfuscated ; ShadowElementName ( Element element , AnnotationMirror shadow ) { } @ Override public String toString ( ) { } @ Override public String baseName ( ) { } public AnnotatedMixinElementHandler . ShadowElementName setObfuscatedName ( String name ) { } public String prefix ( ) { } public String name ( ) { } public String obfuscated ( ) { } public String prefix ( String name ) { } } protected final AnnotatedMixin mixin ; protected final String classRef ; protected final IMixinAnnotationProcessor ap ; protected final IObfuscationManager obf ; AnnotatedMixinElementHandler ( IMixinAnnotationProcessor ap , AnnotatedMixin mixin ) { } protected final boolean remapReference ( String key , String target , Element element , AnnotationMirror inject , AnnotationMirror at ) { } protected final void addFieldMapping ( ObfuscationType type , AnnotatedMixinElementHandler . ShadowElementName name ) { } protected final void addMethodMapping ( ObfuscationType type , AnnotatedMixinElementHandler . ShadowElementName name , String mcpSignature , String obfSignature ) { } protected final void addMethodMapping ( ObfuscationType type , String mcpName , String obfName , String mcpSignature , String obfSignature ) { } protected final boolean validateSingleTarget ( String annotation , Element element ) { } protected final void checkConstraints ( ExecutableElement method , AnnotationMirror annotation ) { } protected final void validateTargetMethod ( ExecutableElement method , AnnotationMirror annotation , AnnotatedMixinElementHandler . AliasedElementName name , String type ) { <START_BUG> String signature = TypeHandle . getElementSignature ( method ) ; <END_BUG> for ( TypeHandle target : this . mixin . getTargets ( ) ) { if ( target . isImaginary ( ) ) { continue ; } MethodHandle targetMethod = target . findMethod ( method ) ; if ( targetMethod != null ) { continue ; } if ( ! ( name . baseName ( ) . equals ( name . elementName ( ) ) ) ) { targetMethod = target . findMethod ( name . baseName ( ) , signature ) ; if ( targetMethod != null ) { continue ; } } for ( String alias : name . getAliases ( ) ) { if ( ( targetMethod = target . findMethod ( alias , signature ) ) != null ) { break ; } } if ( targetMethod == null ) { this . ap . printMessage ( Diagnostic . Kind . WARNING , ( ( ( "Cannot<seq2seq4repair_space>find<seq2seq4repair_space>target<seq2seq4repair_space>for<seq2seq4repair_space>" + type ) + "<seq2seq4repair_space>method<seq2seq4repair_space>in<seq2seq4repair_space>" ) + target ) , method , annotation ) ; } } } protected final void validateTargetField ( VariableElement field , AnnotationMirror shadow , AnnotatedMixinElementHandler . AliasedElementName name , String type ) { } protected final void validateReferencedTarget ( ExecutableElement method , AnnotationMirror inject , MemberInfo reference , String type ) { } }

Fix:
String signature = MirrorUtils . getJavaSignature ( method ) ;